As broadband IP connectivity to homes and offices has become more common, and the speeds of packet-switched communications equipment and the speed of processors have increased, a variety of applications have emerged that utilize IP packet transport as an alternative bearer for voice communications. Generally, such applications are referred to as voice-over-packet services, however, the common forms based on Internet Protocol (IP) are referred to as “Voice over IP” or “VoIP” services.
Additionally, cellular telephone services have grown in popularity. However, cellular telephone services are typically offered at a cost exceeding wireline VoIP telephone services. Thus, when a subscriber is at the home or office, the use of a wireline VoIP is preferred in order to reduce overall communications costs. However, without some degree of integration of the wireline VoIP and cellular services, a subscriber has two separate phone lines, phone numbers, and voice mail services. This presents inconvenience for those wishing to contact a subscriber, as they must be aware of and attempt to contact the subscriber at multiple telephone number. Further, having two independent services is an inconvenience for a subscriber, as multiple voice mail systems must be checked for messages. Additionally, for subscribers who are frequently away from the home or office, the cellular service often becomes a primary point of contact, thereby diminishing the benefit of wireline VoIP service in the home or office.
For the sake of convenience, various approaches to cellular/wireline VoIP integration schemes have been developed. These approaches rely on VoIP technology to provide the “glue” that integrates the cellular service with the wireline VoIP service. Such methods require all calls to or from a subscriber's cellular phone to be “anchored” at a control point in the IP network (e.g., a softswitch or feature server). One mechanism often employed involves the use of wireless intelligent network triggers. However, these triggers are often unavailable because they are already being used to provide the same subscribers with other services (e.g., call screening services, private dialing plans, etc.). Additionally, there are often restrictions on the use of certain triggers while roaming, making them unsuitable to use for call “anchoring.”
Ultimately, none of the above approaches provide full service and feature transparency to the cellular phone subscriber. Specifically, these services fail to provide the subscriber with all of the following attributes, which together yield an enhanced level of cellular/wireline VoIP integration:                A single number that appears as caller identification data when the subscriber calls another party.        A single number used by other parties to call the subscriber, whereby both the subscriber's cellular phone and wireline VoIP would ring, with the incoming call completing to whichever phone (cellular or wireline VoIP) the subscriber chooses to use when answering.        An integrated voice mail box shared by the cellular and wireline VoIP services, and as readily accessible from the wireline VoIP service as from the cellular service.        If one of the phones is in use when the subscriber is alerted for another incoming call, the subscriber has the option of accepting the call from the idle phone, accepting the call from the phone in use as a call waiting call, or allowing the incoming call to be sent to the integrated voice mail box.        No loss of service transparency while roaming.        Maintain an existing cellular phone number, rather than require a new shared number.        Maintain other cellular features to which the subscriber has become accustomed.        Allow use of a third-party Internet Service Provider (ISP) for broadband access over which wireline VoIP service is delivered.        Reject calls directly placed to the wireline VoIP, so as to allow callers only a single telephone number for contacting the subscriber.For calls made to a public safety answering point (PSAP), such as 911 calls in the United States, from a VoIP phone, provide caller identification data corresponding to the wireline VoIP phone, and allow subsequent PSAP-originated call back calls to be made.        